Electrical contact terminals are known which are used to terminate a pair of conductors in a single slot by welding, particularly by laser welding. Such contact terminals are known from U.S. Pat. No. 4,579,404 for use in a single-row electrical connector for terminating the pairs of ground conductors in tri-lead high speed signal transmission cables. A similar but double row connector is known from U.S. patent application Ser. No. 754,785 filed July 12, 1985 and assigned to the assignee hereof. Such terminals require the pairs of ground conductors to be brought together side-by-side near the top of the slot and in interference fit therein for termination remote from the respective signal conductors of the cables. The signal conductors are separately but similarly terminated to respective signal terminals insulated from the ground terminals by the dielectric carrier to which the terminals are secured, and the entire conductor-terminated subassembly is then overmolded forming the connector. Contact sections of the terminals are disposed at the forward end of the connector, ready for electrical engagement with corresponding terminal means of a mating electrical connection means.
When the side-by-side conductors are laser welded, the area of the weld joint of course is wider than if a single conductor were being welded in a correspondingly narrower slot. In both cases the weld joint must join to the sidewalls of the slot whose top surfaces are preferably approximately coplanar with the top portions of the conductor or conductors for optimizing the laser weld termination. However, a typical conductor diameter is about 0.010 inches and the corresponding weld joint for the side-by-side conductors is about 0.040 to 0.045 inches in diameter. A smaller weld joint for only one such conductor requires less energy of the laser beam during welding, and a lower energy incurs less risk of damaging the very small conductor wire.
From U.S. Pat. Nos. 4,602,831 (for a single-row connector) and 4,655,515 (for a double-row connector), both assigned to the assignee hereof, it is known to place individual signal terminals along one side of a dielectric contact carrier, and a single ground plane on the other side of the carrier. In U.S. Pat. No. 4,602,831 all ground conductors of the single row of tri-lead cables (or a tri-lead flat cable) are terminated to the ground plane, singly in respective single width slots by welding such as laser welding. In U.S. Pat. No. 4,655,515 ) each row of cables (or each flat cable) has a contact carrier associated with it having signal terminals on one side and a single ground plane on the other, with each slot of the ground plane receiving a pair of side-by-side ground conductors therein for laser weld termination. Either ground plane is formed by first stamping the plurality of slots in a metal blank near one side edge of the blank, then folding over a portion of the blank along that side edge so that the slots now extend out to the newly formed edge to receive the conductor or pair of conductors. But with either ground plane all grounds of a row of cables (or of the flat cable) are terminated only on the same side of the carrier, and each row of cables or flat cable requires its own contact carrier. Thus, either type of ground plane delimits or complicates the programmability of a double-row connector, and cannot be used in the double-row connector of aforementioned Ser. No. 754,785.
It is desirable to provide a connector for tri-lead cable for high integrity high speed signal transmission using individual ground contact terminals which each receive two small diameter ground conductors in individual slots for separate spaced weld termination without substantially distorting the conductors.
It is also desirable to provide a contact for two conductor wires which includes a separate slot for each conductor, each for receiving a respective one of the conductors for individual weld termination, to eliminate both the necessity for gathering the two conductors to a side-by-side arrangement to be disposed along a single slot, and the necessity for carefully wiping the pair of wires together when being force-fit into a single slot in a manner whereby the conductors are held in a true side-by-side arrangement after being wiped into the slot.
It is further desirable to provide separate slots in a single contact for respective ones of a pair of conductors to reduce the necessary width of the weld joint when the welding is laser welding, to provide an assured laser weld joint without damaging the conductor wire.